Two Enbridge Inc. pipelines were off-line Thursday after the major crude shipper said it discovered a small leak in Michigan.

The spill of less than three barrels was found during planned maintenance inspection and repair work to Line 5 on Wednesday, near the village of Sterling, Mich.

"The pipeline repair and clean up began immediately," spokeswoman Lorraine Little said in an emailed statement.

It's expected the Line 5, which carries 491,000 barrels of per day between Superior, Wisc., and Sarnia, Ont., will be repaired and restarted later Thursday.

Line 1, a 237,000 barrel-per-day line from Edmonton to Superior, has also been shut down due to a backup of crude at Superior. It's expected to start up after Line 5 does.

"We will work with our shippers to assess the impact of the outage," said Little.

"As a precaution, Enbridge is imposing a temporary incremental pressure restriction until a review of similar features from inspection tool runs has been conducted."

Calgary-based Enbridge was responsible for a 2010 pipeline rupture that spilled more than three million litres of oil in southern Michigan.

Cleanup efforts continue from that spill into the Kalamazoo River and Talmadge Creek from a pipeline runs from Griffith, Indiana to Sarnia.

A U.S. federal report detailing the cause of the 2010 rupture is expected to be released this fall, about six months later than expected.

Enbridge is planning to build a $5.5-billion pipeline linking oilsands crude to the port of Kitimat, B.C., after which point the crude would be sent to Asian markets via tanker.

Critics of the project are concerned a spill from the pipeline itself or from large tankers travelling through the Douglas Channel will cause environmental harm.

Enbridge shares rose 13 cents to $39.06 on the Toronto Stock Exchange.